1. Field of the Invention
The present invention relates to a power transmission apparatus for vehicle employing a motor as a power source, and to a vehicle-driving electric machinery system using the power transmission apparatus for vehicle. More particularly, the present invention relates to a power transmission apparatus for vehicle suitable for use in a vehicle including a reduction gear unit and a differential gear unit, and to a vehicle-driving electric machinery system using the power transmission apparatus for vehicle.
2. Description of the Related Art
In a known power transmission apparatus for vehicle employing a motor as a power source, output power of the motor is transmitted to driving wheels through a reduction gear unit to produce a large driving torque, as disclosed in, e.g., JP,A 2001-330111 and JP,A 8-230489.
The system disclosed in JP,A 2001-330111 employs, as the reduction gear unit, a mechanism comprising a plurality of planetary gears.
Also, the reduction gear unit used in JP,A 8-230489 comprises an input shaft coupled to a shaft of a motor, an output shaft disposed parallel to the input shaft and coupled to the driving wheel side, and a transmitting mechanism for transmitting power between the input and output shafts. The transmitting mechanism comprises a first small gear, a first large gear, a second small gear, and a second large gear.
Further, a known power transmission apparatus for vehicle comprises a motor serving as a torque power generator, a reduction gear unit for decelerating torque power outputted from the motor, and a differential gear unit for distributing the torque power, which has been reduced in speed by the reduction gear unit, to left and right wheels. Then, as disclosed in, e.g., JP,A 9-300993, respective axes of the motor, the reduction gear unit, and the differential gear unit are arranged to lie at apexes of a triangle, looking from side.